For understanding of underlying problems of the invention, firstly reference is made to FIG. 28 schematically showing a conventional veneer reeling apparatus which is disclosed by Publication of Unexamined Japanese Patent Application (Kokai) 57-53306 of 1982.
This apparatus has a plurality of endless belts 141 for conveying veneer sheet 140, each trained round a driven front pulley 145 disposed swingable as indicated by double-headed arrow about a pivotal axis defined by a rear pulley (not shown) located on opposite side of the belts 141. The reeling apparatus further includes a take-up reel 143 extending above the upper legs of the belts 141 for winding thereround veneer sheet 140 into a roll 144 and a plurality of sectional touch rolls 142 mounted on a shaft provided just below the reel 143. Each sectional touch roll 142 is located between any two adjacent belts 141 and driven to rotate at a peripheral speed that is slightly higher than the traveling speed of the conveyer belts 141. The shaft carrying the touch rolls 142 is resiliently supported, as indicated by double-headed arrow, and urged so as to make the touch rolls 142 to be in pressing contact with veneer roll 144.
In the above apparatus, veneer reeling is accomplished by rotating the veneer roll 144 by frictional force from the touch rolls 142 pressed thereagainst with a force that is large enough to effect the rotation. Because the veneer roll 144 and the touch rolls 142 are engaged substantially in circle-to-circle contact and hence the length of contact therebetween as seen in veneer conveying direction is rather short, the magnitude of stress resulting from the contact and acting on a unit area between the touch roll 142 and the veneer roll 144 is disadvantageously large. Consequently, the veneer sheet 140 is subjected at the point of contact to a stress that tends to strain or deform the sheet.
On the other hand, a veneer sheet 140 as peeled by a veneer lathe (not shown) comes out therefrom inherently in such a form that the sheet is waved at short intervals. Further, veneer sheet 140 is formed in the lower surface thereof with a number of small cracks, usually called "lathe checks", produced during peeling operation. Thus, veneer sheet generally tends to be deformed easily when it receives an external force and, because a wood veneer sheet is of heterogeneous quality, such deformation takes place variably from one location thereof to another along the line of contact between the veneer sheet and the touch rolls 142 even when it is subjected to application of the same force.
When subjected to the above straining or deforming stress at the touch rolls 142, however, veneer sheet 140 is stretched or extended in the region upstream of the touch rolls 142. Because this extension takes place variably from one location to another of the veneer sheet 140 across the direction in which it is moved, sheet movement tends to be deviated from a straightforward course along the belts 141, with the result that veneer sheet 140 may collide against a frame of the reeling apparatus, thus causing a damage to veneer sheet 140. Furthermore, any excessive extension of veneer sheet 140 causes slack in the sheet 140 as indicated by 140a, which may result in formation of folds. If such folds in the veneer sheet 140 are wound round the roll 144, the sheet 140 is broken at bends of the folds, thereby affecting the veneer quality and yield.